Completion of animal studies on pulmonary effects of vinyl chloride at heavy doses (600 and 300 ppm) with short exposure (a month) will be attempted. Both oncogenetic and non-neoplastic pulmonary effects at the late stage (40 weeks) after the exposure will be investigated. Some animals of 600 ppm will be kept for more than one year to study delayed-responses of the lung tissues to the chemical. A comprehensive evaluation of pulmonary effects of vinyl chloride will be made from the data analysis of three animal studies, (1) heavy doses and long-term exposure, (2) small doses and short-term exposure and (3) heavy doses and short-term exposure. Histopathological studies of human lung sections obtained from deceased workers at vinyl chloride polymerization plants will be continued.